/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.spark.sql.execution.joins

import org.apache.spark.TaskContext
import org.apache.spark.rdd.RDD
import org.apache.spark.sql.catalyst.InternalRow
import org.apache.spark.sql.catalyst.expressions._
import org.apache.spark.sql.catalyst.plans.physical.{BroadcastDistribution, Distribution, UnspecifiedDistribution}
import org.apache.spark.sql.execution.{BinaryNode, SparkPlan}
import org.apache.spark.sql.execution.metric.SQLMetrics

/**
 * Build the right table's join keys into a HashedRelation, and iteratively go through the left
 * table, to find if the join keys are in the HashedRelation.
 */
case class BroadcastLeftSemiJoinHash(
    leftKeys: Seq[Expression],
    rightKeys: Seq[Expression],
    left: SparkPlan,
    right: SparkPlan,
    condition: Option[Expression]) extends BinaryNode with HashSemiJoin {

  override private[sql] lazy val metrics = Map(
    "numOutputRows" -> SQLMetrics.createLongMetric(sparkContext, "number of output rows"))

  override def requiredChildDistribution: Seq[Distribution] = {
    val mode = HashedRelationBroadcastMode(canJoinKeyFitWithinLong = false, rightKeys, right.output)
    UnspecifiedDistribution :: BroadcastDistribution(mode) :: Nil
  }

  protected override def doExecute(): RDD[InternalRow] = {
    val numOutputRows = longMetric("numOutputRows")

    val broadcastedRelation = right.executeBroadcast[HashedRelation]()
    left.execute().mapPartitionsInternal { streamIter =>
      val hashedRelation = broadcastedRelation.value
      TaskContext.get().taskMetrics().incPeakExecutionMemory(hashedRelation.getMemorySize)
      hashSemiJoin(streamIter, hashedRelation, numOutputRows)
    }
  }
}
